Kenai Peninsula Borough is a borough of the U.S. state of Alaska. As of the 2010 census, the population was 55,400. The borough seat is Soldotna.
The borough has a total area of 24,752 square miles (64,110 km), of which 16,075 square miles (41,630 km) is land and 8,677 square miles (22,470 km) (3.4%) is water.
As of the census of 2000, there were 49,700 people, 18,400 households, and 12,700 families residing in the borough. The population density was 1/km² (3/sq mi). There were 24,900 housing units at an average density of 2 per square mile (1/km²). The racial makeup of the borough was 86% white, 7% Native American, 2% Hispanic or Latino (any race), and 4% from two or more races. Black or African Americans, Asians, and Pacific Islanders each were less than 1% of the population. Just under 1% were from other races combined. 1.92% reported speaking Russian at home, while 1.74% speak Spanish.
There were 18,400 households out of which 38% had children under the age of 18 living with them, 55% were married couples living together, 9% had a female householder with no husband present, and 31% were non-families. 25% of all households were made up of individuals and 5% had someone living alone who was 65 years of age or older. The average household size was 2.6 and the average family size was 3.2.
In the borough the population was spread out with 30% under the age of 18, 7% from 18 to 24, 30% from 25 to 44, 26% from 45 to 64, and 7% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 109 males; for every 100 females age 18 and over there were 110 males.
Kenai Peninsula Borough Alaska neighborhoods include: Inlet Woods, Kalifornsky Beach, Main St – Frontage Rd, McGahnville-Holt LampLite, Nikiski, River Quest, Silver Salmon/Strawberry, Spruce-Fireweed-Birch